1998/1999 AIAA Foundation Graduate Team Aircraft Design ...aero-comlab.stanford.edu/plegresl/presentations/wac2000.pdf · Cardinal Design Project Stanford University 1998/1999 AIAA

Cardinal Design ProjectStanford University

1998/1999 AIAA Foundation Graduate Team Aircraft Design Competition:

Super STOL Carrier On-board Delivery Aircraft

Patrick A. LeGresley, Teal Bathke, Angel Carrion,Jose Daniel Cornejo, Jennifer Owens, Ryan Vartanian,

Juan J. Alonso, Ilan Kroo

Department of Aeronautics and AstronauticsStanford University

World Aviation CongressSan Diego, California

October 10, 2000


Outline• Design Requirements & Design Philosophy• Preliminary Weight & Performance Sizing• Configuration Selection & Component Design• Propulsion Selection & Installation• Structural Layout• Drag Estimation• Performance Analysis• Cost Estimation• Design Optimization• Conclusions


Design Requirements• Super Short Takeoff and Landing (SSTOL)

aircraft to provide center-city to center-city travel using river “barges”

• Also fulfill needs of US Navy to replace the C-2 Greyhound for Carrier On-Board Delivery (COD)


Design Requirements (cont.)• Takeoff ground roll of 300 ft, landing ground roll of

400 ft• 1500 nm cruise at 350 knots• Payload of 24 passengers and baggage for

commercial version• Payload of 10,000 lb, capable of carrying two GE

F110 engines for the F-14D, and a spot factor of 60 ft by 29 ft for military version

• Arresting hooks or catapult devices not allowed!• Technology availability date is 2005


Design Philosophy• Investigated two design approaches: tilt-wing and

fixed-wing with upper surface blowing (USB) flaps• Tilt-wing (as opposed to tilt-rotor) concept

demonstrated by Canadair CL-84 and XC-124• USB flaps utilized on NASA Quiet Short-haul

Research Aircraft (QSRA) and Boeing YC-14


Preliminary Weight & Performance• Used to estimate weight, wing area, and thrust or

power to meet performance constraints (cruise speed and range, takeoff and landing ground rolls)

• Fixed-wing with USB flaps:– 48,635 lb takeoff weight– 1000 sq ft wing area– 30,000 lb installed thrust

• Tilt-wing:– 59,922 lb– 700 sq ft wing area– 10,500 installed horsepower


Fuselage• Fuselage laid out around engine containers:

x 4

Turbine orAfterburnerContainer Total of 4 containers for the 2 GE F110 Engines


Fuselage (cont.)

Military Version with two GE F110 engines for F-14D

Passenger version with accommodation for 24 passengers


Wing• Highly constrained by spot factor requirement

(60 ft x 29 ft, wing folding allowed)

• Final design incorporated wing pivoting and folding


Propulsion & High Lift• Two different concepts for high lift:

(I)Airflow over wing without BLC

(II)USB Concept

(III)BLC used to delay boundary layer build-up

Upper Surface Blowing (USB) Flaps

Tilt-wing


Propulsion & High Lift (cont.)• Analyzed using methodology in Aerodynamics of

V/STOL Flight by McCormick

• Flight test and wintunnel data for ‘sanity’ check

Sample Variation of Lift Coefficient

Engine Installation0 5 10 15 20 25 30 35 40 45

0

1

2

3

4

5

6

Momentum Coefficient, C µ

Lif

t Coe

ffic

ient

, CL

δf = 10 deg

α = 0 degCµ = Thrust/(q barS ref)


Structural Layout• Based on ‘typical’ configurations of cargo aircraft

and consists of frames, longerons, ribs, and spars

• Efforts to make use of advanced materials where useful and cost effective


Wing Structure


Empennage Structure


Drag Estimation• Drag build-up approach: drag of each major

component computed, plus interference effects• Induced drag computed as function of wing/body lift

coefficient

0 0.1 0.2 0.3 0.4 0.5 0.6 0.70

0.01

0.02

0.03

0.04

0.05

0.06

0.07

Lift Coefficient

Dra

g C

oeff

icie

nt

Drag Polar and L/D vs. CL for M = 0.61

Drag PolarL/D vs. CL

12

10

8

6

4

2

0

Lift-

to-D

rag

Rat

io

Start Cruise

End Cruise

Cruise Drag


Performance Analysis• Equations of motion numerically integrated to

compute takeoff and landing ground roll• Climb rate calculated from engine data & drag polar

30 35 40 45 50 55 100

150

200

250

300

350

400

450

SL, SA + 27 deg F

Landing

Takeoff

Weight, W (1000s lbs)

Gro

un

dro

ll, S

g (

ft)

0.2 0.3 0.4 0.5 0.6 0.7 0.8 -2000

0

2000

4000

6000

8000

10000

Mach Number, M

Ra

te o

f C

limb

, R

C (

ft/m

in) 0

10K

20K

30K

40K

Weight = 40,000 lbsMaximum Continuous Thrust

Takeoff and Landing Ground Rolls AEO Climb Rate


Performance (cont.)• Specific range computed from drag polar and

engine data for various weights• Range calculated by integrating specific range,

taking into account reserves requirements

150 200 250 300 350 400 450 0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

Speed, V (knots)

Sp

eci

fic

Ra

ng

e,

SR

(n

m/l

b)

30,000

35,000

40,000

45,000 Valid for h = 37,000 ft

0 500 1000 1500 2000 2500 3000 3500 0

5

10

15

20

25

Range, R (nm)

Pay

load

, W

PL

(100

0s lb

s)

Design Payload

Design Range Ferry Range

Specific Range Payload-Range


Cost Estimation• Cost estimation method based on statistical data gathered

for many existing aircraft

• Research, Development, Test, and Engineering (RDTE), Acquisition, Operating, and Disposal costs were computed, leading to the Life Cycle Cost (LCC)

27%

24%26%

< 1%

6%

17%

FlyingMaintenanceDepreciationLanding Fees,Nav.,TaxesFinancingIndirect

Military Version Operating Costs: 8.44US$/nm

Block Distance: 1500 nm

Commercial Version Operating Costs: 8.16US$/nm

< 1%8%

91%

1%

RDTE PhasesAcquisitionOperating CostsDisposal

Military Version Life Cycle Cost: $155B (750 military airplanes)

Commercial Version Life Cycle Cost: $149B (750 commercial airplanes)

Operating Cost BreakdownLife Cycle Cost


Design Optimization• Various subsystem analyses (high lift, weight,

propulsion, performance, cost, etc.) were combined into a collaborative optimization code

• The goal of the optimization was to produce the best design (in this case as measured by life cycle cost) which met all of the design requirements –takeoff and landing ground roll, cruise speed and range

• Constraints for FAR / MIL certification such as stability, climb gradients, tipover, etc. were also applied


Design Optimization (cont.)


Design Optimization (cont.)• A final design was selected based on the

relative costs of the various designs:

VerticalTakeoff Tiltwing

ShortTakeoff Tiltwing

Short Takeoff Fixed Wing

DOC $9.06/nm $7.82/nm $7.03/nm

IOC $1.81/nm $1.56/nm $1.41/nm

Fuel Price $1.20/gal $1.20/gal $1.20/gal

Engine Price (per engine)

$1.09 M $0.81 M $0.52 M

AEP $20.8 M $18.0 M $17.1 M

AMP $19.7 M $17.3 M $16.7 M

LCC $200.6 B $172.1 B $154.7 B

Cost Comparison

Final Three-View


Trade Study on Performance Requirements

• Although performance requirements were specified, constraints were varied to analyze effect on LCC

• One of the more interesting is that for takeoff ground roll:

250 300 350 400 450 500 5501

1.1

1.2

1.3

1.4

1.5

1.6x 10

11

Takeoff Ground Roll(ft)

Lif

e C

ycle

Cos

t, L

CC

(US$

)

Cardinal Design

Variation of Life Cycle Cost with Takeoff Ground Roll Constraint


Conclusions• Upper Surface Blowing (USB) flaps and tilt-wing

considered as means to achieve Super Short Takeoff and Landing (SSTOL)

• Subsystem analyses methods developed for use in collaborative optimization

• A fixed-wing design with USB flaps was selected for its lower Life Cycle Cost

• Design studies showed that a relaxed takeoff constraint would have a significant effect on Life Cycle Cost

Documents

1998/1999 AIAA Foundation Graduate Team Aircraft Design ...aero-comlab.stanford.edu/plegresl/presentations/wac2000.pdf · Cardinal Design Project Stanford University 1998/1999 AIAA